Electric induction furnace



June 15 1926.

D. L SUMMEY ELECTRIC INDUCTION FURNACE Filed May 28 1923 2 Sheets-Sheet1 2 auoautoz .Eune 15 1926. 1,589,266

L. SUMMEY ELECTRIC INDUCTION FURNACE Filed May 28, 1925 2 Sheets$heet 28 r M1 ate; MU;OZ

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Patented June 15, 1926.

UNITED STATES 1,589,266 PATENT OFFICE.

DAVID L. SUMMEY, OF WATERBURY CONNECTICUT.

ELECTRIC INDUCTION FURNACE.

Application 'filed May 28,

This invention relates to electric induction furnaces.

It is the principal object of the invention to provide an improvedinduction furnace, and particularly one that avoids stirring of the bathby electrical effects.

I/Vith this general object in view, the invention consists in thecombinations, details of construction and arrangements of parts whichwill first be described in connection with the accompanying drawings andthen more particularly pointed out.

In the drawings:

Fig. 1 is a view in side elevation of a furnace constructed inaccordance with the in vention;

Fig.2 is a top plan view with parts broken away;

Flg. 3 is a vertical cross sectional view through the furnace;

Figs. 4 and 5 are cross-sectional views taken on the lines 44, 5-5respectively of Fig. 3; and

Fig. 6 is a vertical sectional view with parts in end elevation, showinga modified construction.

Referring to the drawings, there is pro vided, in the presentembodiment, a furnace body comprising a shell 21 and a lining 22 ofsuitable refractory material. This body is generally bowl shaped, havingflat sides and bulging ends, as more clearly appears in the drawings.For convenience, the main shell may be formed in two parts, the top parthaving a flange 23 resting on a similarflange 24 on the bottom part. Atthe top .of the furnace is a charging opening 25.

In constructions embodying the invention to the best advantage thehearth or space for the charge is in the form of a plurality ofsymmetrically arranged pockets or chambers. To this end, as here shownas an example, extending across the interior of the furnace below thecharging opening is a ridge 26 of refractory material convenientlyformed as a continuation of the furnace lining. This ridge has slopingor curved sides, as appears in Fig. 3 and divides the furnace interiorinto two diametricall opposed pockets 27, 28, opening out of tie commonspace between opening 25 and the ridge 26, and extending downwardly, asmore fully appears in Fig. 3. In the embodiment illustrated the chargingopening 25 is centered on the main vertical axis of the furnace body andthe pockets 27, 28 are sym- 1 923. Serial No. 641,801.

metrical with this axis, the tendency of the ridge 26 being to dividethe charge into the two pockets.

The invention includes a transformer primary and core and a secondarychannel,- that is, a channel for the metal bath which plays the part ofthe secondary. In constructions embodying the invention to the bestadvantage the secondary channel is located in a horizontal plane and issymmetrical with and equidistant from the primary. Although capable ofvarious constructions, in that here shown as an example, near the bottomof the furnace, is a circular channel 29 lying in a horizontal plane andconcentric with the charging opening. As shown, the channel 29 iscircular in cross section.

Extending across the furnace below the crest of ridge 26, there isprovided a trans former casing member 30, the furnace body beingsuitably formed to accommodate the transformer elements as appears in'the drawings. The transformer here illustrated includes a laminated core31 in the form of a closed E. The central leg 32, in cross section, hasthe form of a Greek cross and around this central leg is wound acylindrical primary coil 33, located concentrically with the secondarychannel 29.

With a secondary element symmetrical with and equidistant from therimary ele ment, the transformer is capa le of hi h efficiency, thusmaking possible ahighly efiicient induction furnace. Furthermore, witha. secondary channel such as that described, the length gives a goodpower factor, and the length can be increased to obtain more power, asfor low resistance metals, without increasing the head of metal and soincreasing pressure on the lining. The construction further lends itselfto flexibility of use, as more heating capacity can be obtained eitherby increasing the voltage for a given resistor channel or by increasingthe length of the resistor channel, with the same cross section, for agiven voltage.

There is provided means of communication between the pockets 27, 28 andthe channel 29. Although capable of various constructions, in theembodiment here illustrated, opening out of the pockets 27, 28, near thebottom thereof, are two diametrically opposed passageways 34, 35 opening.into the channel 29.

Suitable electric current being supplied to the primary 33 of thetransformer, the metal bath in the channel 29 acts as a secondary andcurrents. are induced therein, as will be apparent to those skilled inthe art, these induced currents heating the bath.

There is provided means for causing a mechanical stirring of the bathand in constructions embodying the invention to the bestadvantage thefurnace body is period- .i'ca'lly rocked in the direction of thepassages 34, 35-. \Vhile this may be accomplished in various ways, thefurnace may be pivoted off center, whereby it is tilted one way bygravity, mechanism being provided for tilting it in the oppositedirection. Although capable of various constructions, in that hereillustrated as an example, at the sides of the furnace body are gudgeons36 pivotally mounted in a frame 37 later referred to. It will be notedthat the pivots just described are slightly off center. In other words,the pivots are offset from the center of gravity so that the tendency ofthe furnace is to tilt to the left as viewed in Fig. 3..

While the mechanism for tilting the furnace in the opposite directionmay vary, it may conveniently comprise an oscillating member engagingthe lower side of an abutment on the furnace. As here illustrated as anexample, pivoted to a suitable support, such as a bracket 38 hung fromthe charging floor 39, is a bell crank lever 40. Pinned to one arm ofthis bell crank is a yoke 41 on a link 42 oscillated by an eccentric 43on a slow moving shaft 44 suitably connected with a source of power. Thefree arm of the bell crank engages the under side of the flange 23,which forms, with flange 24, an abutment. Upon rotation of the eccentric43, the bell crank will alternately tilt the furnace to the right asviewed in Fig. 3 and permit tilting in the opposite direction under theforce of gravity. Thus the furnace is periodically rocked back and forthon its pivots. I 1

When the furnace is tilted, for example to the right as viewed in'Fig.3, the molten bath in the channel'flows through the passage 34 into thepocket 27 to make contact with and further the melting of more of thecharge. Upon the reverse tilt the flow is into the opposite pocket witha like eflect. This alternate movement of the furnace effectively stirsthe bath and this stirring is entirely mechanical, as distinguished fromstirring by various electrical effects such as are known in the art.

With the construction described there is no local overheating as thebath in the channel must circulate. Furthermore, the surge of the bathand settling of the charge as the.

furnace rocks, prevents matting and avoids the manual agitation of thecharge during melting that is ordinarily found necessary with inductionfurnaces. There is no so-called pinch effect because any tendency to apinch effect in the resistor circuit is counteracted by a similar effectelsewhere in that circuit.

There is provided means for tilting the furnace for pouring and this isaccomplished without interfering with the stirring mechanism. Althoughcapable of various constructions, in that illustrated as an example inFigs. 1 to 5, in the end of the furnace body opposite the bell crank 40is a passageway 46 leading to a spout 47. At this same end of thefurnace, the frame 37 is pivotally connected, as at 48, 49, to astandard or support 50. Near the bottom of the frame 37 is pivotallyconnected a link 51 mounted on the piston rod 52 of an air hoist 53, orthe like, of any suitable construction.

Upon operation of the air hoist the frame 37 and furnace body, moving asa unit, are tilted on the pivots 48, 49 until the melted charge ispoured out via the spout 47. It will be noted that this tilting-forpouring is in the direction of the passage 34. With this constructionthe furnace may be completely emptied, as the passage 34 opens out ofthe lowest part of the channel 29.

It may be desirable to retain part .of the melted charge when pouringtakes place. This may be accomplished, forexample, by pouring in adirection at right angles to that described. Fig. 6 illustrates amodification in which the frame pivots are displaced 90 from the pivots48, 49, one pivot 54 being shown. The spout 55 and pouring passage 56are, similarly displaced, being in one side of the furnace instead of atthe end. With this construction, when the furnaceis tilted for pouring,the lowest part of the channel 29 is cut off, and the molten metalgravitating into that part of the channel remains thereto aid instarting the next melt.

lVith both of these constructions, the abutment formed by flanges 23, 24simply lifts away from the end of the bell crank 40 when the furnace ispoured. There is, therefore, no interference between the rocking and thepouring and no disconnections or other manipulations are necessary forpouring.

The operation of the furnace will be clear from the above withoutfurther description.

What is claimed is:

1. In an electric induction furnace, in combination, a furnace 'bodyhaving a channel for the bath, a primary transformer element, the bathin said channel serving as a secondary and being heated by the currentsinduced therein, and meansfor causing the furnace body to rock, at suchintervals and in such manner as to stir the bath.

2. In an electric induction furnace, in combination, a furnace bodyhaving a channel for the bath, located in a horizontal plane, a primarytransformer element, the bath in said channel serving as a secondary andbeing heated by the currents induced therein, and means for causing thefurnace body to rock at such intervals and in such manner as to stir thebath.

3. In an electric induction furnace, in combination, a furnace bodyhaving a channel for the bath, a space for the charge and a plurality ofcommunicating passages between said channel and the charge space, aprimary transformer element, the bath in the channel serving as asecondary and being heated by the currents induced therein, and meansfor causing the furnace body to rock in the direction of said passagesat such intervals and in such manner as to stir the bath.

4. In an electric induction furnace, in combination, a furnace bodyhaving a chan nel for the bath, a charging opening, a plurality ofsymmetrically arranged pockets for the charge, andcommunieating'passages between said pockets and the channel, and aprimary transformer element, the bath in the channel serving as asecondary and being heated by the currents induced therein.

5'. In an electric induction furnace, .in combination, a furnace bodyhaving an annular channel for the bath, a charging opening, a pluralityof symmetrically arranged pockets for the charge, and communicatingpassages between said pockets and the channel, and a primary transformerelement, the bath in the channel serving as a secondary and being heatedby the currents induced therein.

6. [in an electric induction furnace, in combination, a furnace bodyhaving an annular channel for the bath, a charging opening, a pluralityof symmetrically arranged pockets for the charge, and communicatingpassages between said pockets and the channel, a primary transformerelement, the bath in the channel serving, as a secondary and beingheated by the currents induced therein, and means for causing thefurnace body to rock in the direction of said passages, thereby to stirthe bath.

7. In an electric induction furnace, in combination, a furnace bodyhaving an annular channel circular in cross section for the bath, and acylindrical primary transformer element concentric with said channel,the bath in said channel serving as a secondary and being heated bycurrents induced therein, and means for causing the furnace body to rockthereby to stir the bath,

8. In an electric induction furnace, in combination, a furnace bodyhaving a channel for the bath, a primary transformer element, the bathin said channel serving as a secondary and being heated by the cur rentsinduced therein, means for pivotally mounting the furnace body offcenter of gravity, ivhereby the furnace body tends to tilt, and meansfor periodically tilting the furnace body in the opposite direction,thereby to stir the bath.

9. In an electric induction furnace, in con'ibination, a furnace bodyhaving a chan- .nel for the. bath, wherein the bath may be heated bycurrents induced therein, means for pivotally mounting the furnace bodyoft center of gravity, whereby the body tends to tilt, an abutment onsaid body, a bell crank lever engaging said abutment, and means foroscillating said bell crank thereby to tilt the furnace bodyperiodically in a direction opposite to said gravitational tilt. theresulting rocking of the furnace body erving to stir the bath.

10. In an electric induction furnace, in combination, a furnace bodyhaving a channel for the bath wherein the bath may be heated by currentsinduced therein, means for causing the furnace body to rock at suchintervals and in such manner as to stir the bath, and means for tiltingthe furnace body to pour the melted charge.

11.111 an electric induction furnace, in combination, a support, a framepivotally mounted in said support, a furnace body pivotally mounted insaid frame and having a channel for the bath wherein the bath may beheated by currents induced therein, means for causing the furnace bodyto rock on its pivot at such intervals and in such manner as to stir thebath. and means for tilting the frame on its pivot, thereby to move thefur nace to pour the melted charge.

12. In an electric induction furnace, in combination, a furnace bodyhaving an annular, horizontal channel for the bath, a

plurality of pockets for the charge, communicating passages between saidpockets and said channel, and a pouring pas-age leading to a spout,means for causing the furnace body to rock in the direction of saidpassages, and means for tilting the furnace body in the direction of oneof said passages to pour the charge, whereby the lowest part of thechannel has an outlet when in pouring position.

13. In an electric induction furnace. in combination, a furnace bodyhaving a chain nel for the bath wherein the bath may be heated bycurrents induced therein. and a charging opening, a ridge, havingsloping sides, located below the charging opening and dividing thefurnace interior into two symmetrically arranged pockets for the charge,the furnace body having commnnh eating passages between said pockets andsaid channel, and means for causing the furnace body to rock in thedirection of said passages, thereby to stir the charge.

1 t. In an electric induction furnace, in combination, a furnace bodyenclosing a hearth having a plurality of symmetrically arranged pockets,the furnace body having an annular channel for the bath, circular incross section and arranged symmetrically with respect to said pockets, acylindrical primary transformer elementsymmetrically located withrespect to said channel, molten metal in the channel acting as asecondary and being heated by currents induced therein, the furnace bodyhaving symmetrically located passages connecting said channel with saidpockets.

15. In an electric induction furnace, in combination, a furnace bodyenclosing a hearth having a plurality of syimnetrically arrangedpockets, the furnace body having an annular channel for the bath,circular in cross section and arranged symmetrically with respect tosaid pockets, a cylindrical primary transformer element symmetricallylocated with respect to said channel, molten metal in the channel actingas a secondary and being heated by currents induced therein, the furnacebody having symmetrically located passages connecting said channel withsaid pockets, and means for rocking the furnace, thereby to stir thecharge.

16. In an electric induction furnace, and in combination, a furnace bodyhaving a channel for the bath and enclosing a space for the charge, thebody having a ridgelike portion extending upwardly to form twosymmetrically arranged pockets for the charge in the lower part of saidspace, and having comn'iunicating passageways between the lower parts ofsaid pockets and said channel, and a primary transformer element, thebath in said channel serving as a secondary and being heated by thecurrents induced therein.

In testimony whereof, I have hereunto set my hand.

DAVID L. SUMMEY

